1. Field of the Invention
This invention relates to a height adjustment apparatus for a baby walker, more particularly to a double-lock height adjustment apparatus.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional height adjustment apparatus for a baby walker (4) is disposed between a seat (41) and a U-shaped tube (42) and includes a positioning plate (1), a retaining member (2) and a controlling member (3). The U-shaped tube (42) has a radial hole (422) formed therethrough. The positioning plate (1) has a row of positioning holes (11) and four fastening holes (12) and is screwed to the underside of the seat (41). The retaining member (2) has a U-cross-sectioned body disposed around the upper portion of the U-shaped tube (42), and a slot (21) formed through the central portion thereof. Two lugs (22) project outward from one side of the body of the retaining member (2) and have central holes (221) formed therethrough. A fastening plate (23) projects outward from the other side of the body of the retaining member (2) and has two end holes (221') in two end portions thereof, and a middle hole (24) in the middle portion thereof. A positioning pin (421) is fixed in the hole (422) of the U-shaped tube (42) and extends through the slot (21) so as to position the retaining member (2) on the U-shaped tube (42). The controlling member (3) has a hollow projection (311) and four holes (312) (only two are shown in FIG. 2) formed therethrough in alignment with the holes (221, 221') of the retaining member (2) so that four lock bolts (not shown) extend through the holes (B12) of the controlling member (3) and the holes (221, 221') of the retaining member (2), thereby confining the U-shaped tube (42) between the retaining member (2) and the controlling member (3). Because the positioning plate (1) is positioned between two of the lock bolts that extend through the holes (221) of the retaining member (2) and between another two of the lock bolts that extend through the holes (221') of the retaining member (2), the assembly of the U-shaped tube (42), the retaining member (2) and the controlling member (3) is retained on and is slidable relative to the positioning plate (1) and the seat (41).
A movable lock pin (32) is mounted in the projection (311) of the controlling member (3) and is biased by a spring (321) to extend from the projection (311) and through one of the positioning holes (11) of the positioning plate (1) so as to engage the middle hole (24) of the retaining member (2). A pull member (322) is mounted on the projection (311) and is connected securely to the movable lock pin (32).
Referring to FIG. 3, when one desires to adjust the height of-the baby walker (4), the pull member (322) is pulled so as to disengage the movable lock pin (32) from the middle hole (24) of the retaining member (2) and from the positioning hole (11) of the positioning plate (1), thereby allowing movement of the movable lock pin (32) from one of the positioning holes (11) to another. Accordingly, the U-shaped tube (42) can be moved relative to the positioning plate (1) which is fastened to the seat (41) from the position of FIG. 3 to the position of FIG. 4 or 5.
Although the height of the baby walker can be easily adjusted, a baby carried thereon may pull the pull member (322), thus resulting in an abrupt downward movement of the seat or even in collapsing of the baby walker. As a result, the baby may get hurt.